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tional cost of rat-proofing is slight indeed in comparison with 

 the advantage gained. Cellar walls, if made of stone, should 

 be laid in concrete, and the cellar or basement floor should be 

 of medium concrete 3 inches thick overlaid with cement. Such 

 floors will be better drained and will not be undermined by 

 rats if 8 or 10 inches of gravel can be put in as a foundation 

 and the concrete laid upon it. If, then, the walls on which the 

 sills of the house rest are of brick, stone or concrete, rising 2 

 feet or more above the ground, and the doors, windows and 

 other openings are well protected, there will be little chance for 

 rats to gain access to the building. A rat must have some 

 shelter and something to stand on to gnaw through the wooden 

 wall of a house. A veranda sometimes offers such an oppor- 

 tunity, as the rats may find some support beneath it from 

 which they may penetrate the wall. Verandas and walks 

 should be made of concrete or similar material laid on gravel, 

 with side walls extending at least 2| feet under ground. Plank 

 walks furnish excellent accommodations for rats and should be 

 done away with. As an additional safeguard the walls of the 

 house above the sills may be filled with cement up to about 

 2 feet above the floor. This will prevent rats burrowing into 

 the wall. If upper windows are left open, and unscreened, rats 

 may enter them by way of trees near the house or vines climb- 

 ing upon it. If rats gnaw the doors all outer doors should be 

 provided with metal strips 6 inches wide at the bottom, and 

 each outer door or screen door should have a spring or check 

 device to keep it closed. Cellar windows, skylights and venti- 

 lators should be screened with galvanized wire netting of 

 half-inch mesh and not less than 20 gauge. Any unused 

 chimney should have all openings closed with tight-fitting 

 covers and the top screened. Traps that rats cannot crawl 

 through should be used in all water-closets; otherwise they 

 maj' enter the house from the sewer. All holes where pipes 

 pass through cellar walls should be closed with concrete. In 

 large storehouses or warehouses, particularly those without 

 cellars, it is a great advantage to make the lower floor of 

 reinforced concrete. In stores or dwelling houses where this 

 cannot be used solid concrete walls and a double floor with 

 1^-inch mesh wire netting of not less than 20 gauge nailed 



